The present invention relates to a method for determining at least one magnitude characteristic of a geological formation chosen from a so-called characteristic set formed of three magnitudes designated respectively by K.sub.1C, .sigma..sub.3 and H.sub.F which are the stress intensity factor of the formation, the minimum in situ principle stress and the fracture height, knowing at least one of these magnitudes.
It is obvious that the last magnitude depends not only on the geological formation but also but also on the fracturing conditions.
To have a good knowledge of a geological formation, more especially for carrying out fracturing thereof, it is necessary to know the values of K.sub.1C and .sigma..sub.3.